show pragress bar while downloading file - ios

Question

Hi in my application I have a file in URL I want download to my document folder in my application while downloading the file i want to show the progress bar. So I have used the MBProgressHUD for that but its not working properly its showing late please tell me how to resolve this one.
My code:
- (IBAction)down:(id)sender {
UIButton *btn = (UIButton *)sender;
spinner = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
spinner.mode = MBProgressHUDModeCustomView;
[spinner setLabelText:#"downloading....."];
[spinner setLabelFont:[UIFont systemFontOfSize:15]];
[spinner show:YES];
NSURL *url = [NSURL URLWithString:fileurl];
NSData *urlData = [NSData dataWithContentsOfURL:url];
if ( urlData )
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:#"%#/%#", documentsDirectory,name];
[urlData writeToFile:filePath atomically:YES];
}
[activityIndicatorObject stopAnimating];
[spinner hide:YES];
[spinner removeFromSuperViewOnHide];
}
I have used the above code its taking too much time to show the MBProgressHUD Please tell me how to resolve this issue I have stuck here for time.
Thanks..

Answer 1

You have to change in your code as below..
- (IBAction)down:(id)sender {
UIButton *btn = (UIButton *)sender;
//spinner = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
[MBProgressHUD showHUDAddedTo:self.view animated:YES];
//spinner.mode = MBProgressHUDModeCustomView;
//[spinner setLabelText:#"downloading....."];
//[spinner setLabelFont:[UIFont systemFontOfSize:15]];
//[spinner show:YES];
NSURL *url = [NSURL URLWithString:fileurl];
NSData *urlData = [NSData dataWithContentsOfURL:url];
if ( urlData )
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:#"%#/%#", documentsDirectory,name];
[urlData writeToFile:filePath atomically:YES];
}
//[activityIndicatorObject stopAnimating];
//[spinner hide:YES];
//[spinner removeFromSuperViewOnHide];
[MBProgressHUD hideHUDForView:self.view animated:YES];
}
Enjoy Code..

Answer 2

I suspect what you are experiencing are concurrency issues with the above code. I'm assuming the URL you are fetching is from over a network. The NSData method dataWithContentsOfURL: is blocking the main thread before the operating system has a chance to call setNeedsDisplay on the spinner, which also happens on the main thread, and this could explain why it's showing up late.
The solution would be to make some sort of asynchronous request, to fetch the file, with a completion handler, so your application can do tasks etc upon completion, (like stopping the activity indicator, persisting the file to local storage etc).
This is what the documentation has has to say about the dataWithContentsOfURL: of NSData class :-
Important: Do not use this synchronous method to request network-based URLs. For network-based URLs, this method can block the current thread for tens of seconds on a slow network, resulting in a poor user experience, and in iOS, may cause your app to be terminated.
Instead, for non-file URLs, consider using the dataTaskWithURL:completionHandler: method of the NSSession class.